Fluid device



Oct. 11, 1966 Filed July 7, 1964 G. A. WAHLMARK 3,27735 FLUID DEVICE 5Sheets-Sheet l INVENTOR.

Oct. 11, 1966 G. A. WAHLMARK FLUID DEVICE .'3 Sheets-Sheet 2 Filed July7, 1964 Oct. 11, 1966 G. A. WAHLMARK 3,277,335

FLUID DEVICE s sheets-sheet 5 Filed July '7, 1964 INVENTOR.

United States Patent O 3,277,835 FLUID DEVICE Gunnar A. Wahlmark,Asjogle, Kristdala, Sweden Filed .lluly 7, 1964, Ser. No. 380,785 10Claims. (Cl. 10S- 162) The present invention relates in general to fluiddevices. It deals more particularly with fluid devices of the swashplate type.

Swash plate type fluid devices are, in general, well known. Anillustrative variable displacement pump is shown in the applicantsco-pending application, Serial No. 838,868, filed September 9, 1959, nowPatent No. 3,136,264, entitled, Variable Displacement Fluid Device. Itshould be understood, however, that fluid devices of this type mayembody either fixed or variable displacement constructions, in additionto operating as either pumps or motors.

Most swash plate type fiuid devices employ a cylinder mechanismconnected to a swash plate mechanism by a plurality of pistons. Thepistons are reciprocable in the cylinder barrel of the cylindermechanism, which is rotatable against a bearing surface within thecasing of the device. In a fixed displacement fluid device, the bearingsurface is conventionally formed on a stational bearing plate seated inthe casing or housing. In contrast, in a variable displacement fiuiddevice the bearing surface is conventionally formed on an arcuatelymovable port block housing or the like. In either case, it is imperativethat the cylinder barrel rotate in substantially fluid tightrelationship against the bearing surface to assure proper operation ofthe device.

It is an object of the present invention to provide an improved swashplate type fluid device.

It is another object to provide a new and improved locking arrangementfor preventing unseating of the cylinder barrel from optimum bearingrelationship against its complementary bearing surface.

It is yet another object to provide a locking arrangement of theaforedescribed character for both fixed and variable displacement pumpsor motors.

It is still another object to provide a simple and inexpensive cylinderbarrel locking arrangement.

The foregoing and other objects are realized in accord with the presentinvention by providing a resilient locking ring releasably retainedbetween the periphery of the cylinder barrel and its mounting element.In one aspect of the invention, the locking ring preloads the cylinderbarrel against its complementary bearing surface to assure intimatecontact of the barrel With the bearing surface at all times. In anotheraspect of the invention, the locking ring exerts axial pressure on thecylinder barrel only during specific stages of operation of the deviceand the barrel rotates in virtually frictionless relationship with thering in normal operation.

The invention, both as to its organization and method of operation,taken with further objects and advantages thereof, will best beunderstood by reference to the following description taken in connectionwith the accompanying drawings in which:

FIGURE l is a vertical sectional view taken through a variabledisplacement fluid pump embodying features of the present invention;

FIGURE 2 is a horizontal sectional view taken through the pumpillustrated in FIGURE l;

FIGURE 3 is a sectional view taken along line 3-3 of FIGURE 2;

FIGURE 4 is a sectional vieW taken along line 4-4 of FIGURE 1, withparts removed;

FIGURE 5 is an enlarged sectional view of a first form of cylinderbarrel locking arrangement embodying features of the present invention;and

FIGURE 6 is an enlarged sectional veiw of a second form of cylinderbarrel locking arrangement embodying features of the present invention.

Referring now to the drawings, and particularly to FIGURES l and 2, avariable displacement fluid pump embodying features of the presentinvention is seen generally at 10. The pump 10 is designed to pumppetroleum fuel to a gas turbine engine (not shown) through its inletport 11 and expels it under pressure through its outlet port 12 in thepump casing 15. The pump 10 is driven by the drive shaft 16 from asuitable power take-off in the turbine engine.

The casing of the pump 10 comprises a generally cylindrical body 20closed at one end 21 and having an end cap 22 secured by bolts 24 overits open end 25. An O-ring seal 26 suitably disposed between the cap 22and the open end of the body 20 provides a uid tight seal therebetween.The body 20 and the cap 22 are preferably formed of a hardened alloysteel.

The inlet port 11 communicates with the interior of the casing 15 viathe inlet passage 27 through the closed end 21 of the body 2f). Acorresponding outlet passage 28 connects the outlet port 12 with theinterior of the casing 15 through the closed end 21. A port cap 30 ismounted flush against the closed end 21 of the body 20 and fixed inposition on the closed end by a series of pins 31 (only one of which isshown). An arcuate bearing surface 32 is formed on the inside of the capfor slidably seating the cylinder mechanism 33 of the pump 10.

The cylinder mechanism 33 includes a port block housing 4t) which isslidable on the arcuate bearing surface 32 of the cap 30. A cylinderassembly 41 is seated in the housing for rotation about a cylinder axispin 43. The port block housing 40 is generally cup-shaped inconfiguration and is also preferably formed of a hardened alloy steel.

The axis pin 43 extends through a complementary cylindrical aperture 47in the base 48 of the housing 40 and is necked down at its outer end 49to slide in the arcuate track 50 formed in the center of the arcuatebearing surface 32 on the port cap 30. The necked down end 49 of the pin43 is retained in the track 50 by a laterally extending lip 5.1 on thepin Iwhich slides in a complementarily formed lateral recess 52 in thetrack.

The base 48 of the port block housing 40 includes an arcuate faceportion 53 which actually slides against the bearing surface 32, and anadjacent flat face portion 54.

As will be noted, the pin 43 extends approximately through the center ofthe flat face portions 54 into the track S0. Bracketing the pin 43 inthe base 48 and extending therethrough are a fluid inlet, passage 55 anda fluid outlet passage 56. The outer end section of each passage 55 and56 is enlarged, as at 58, and seats a port shoe assembly 59. Since theport shoe assemblies 59 and corresponding receiving end sections 58 ofthe passages 55 and 56 are identical, corresponding components of eachare identified by corresponding reference numerals.

Each port shoe assembly 59 comprises a vertically elongated port shoeblock 61 having passage means 62 extending therethrough. The passagemeans 62 through each shoe block 61 is elongated sufiiciently to be inconstant communication with a corresponding passage 65 through the portcap 30 regardless of the displacement setting of the variabledisplacement pump 10. O-ring seals 66 assure fiuid tight communicationbetween the inlet passage 27 and the outlet passage 28, extendingthrough the closed body end 21, and corresponding port cap passages 65.

Each port shoe block 61 has an arcuate outer surface 67 which is urgedagainst the complementary arcuate bearing surface 32 on the port cap 30by a plurality of coil springs 71 seated in suitably formed wells 72 inthe housing base 48. The springs 71 bear against a corresponding washermember 73 underlying each port shoe block 61 Suitable sealing elements74 encircle each port shoe block 61.

Seated against the inner surface 75 of the base 48 in the port blockhousing is a circular bearing plate 76 which is fixed against movementon the surface 75 by a series of pins 77 (only one shown). The bearingplate 76 is pierced by a conventional kidney shaped inlet port 78 and anoppositely disposed kidney shaped outlet port 79. The cylinder assembly41 is mounted for rotation in bearing relationship against the outerbearing surface 80 of the plate 76.

As seen in FIGURE 2, the axis pin 43 extends through an axially disposedaperture 81 in the bearing plate 76.

The pin 43 has a transversely disposed key 82 extending through asuitably formed aperture in its mid-section; the key seating in keyslots 83 radiating from the aperture 81 to obviate any tendency in thepin 43 to rotate and bind in its track 50 during operation of the pump10. Fluid is transmitted through the pin 43 for lubrication purposes inthe pump through an axial lubrication passage 84 extending the length ofthe pin 43 and terminating adjacent the track 50 in a laterallubrication passage 85.

The cylinder assembly 41 includes a cylinder barrel 90 having a bearingface 91 seated in bearing relationship on the bearing surface 80 of theplate 76. The cylinder barrel 90 has an axially disposed bore 92extending through it which receives the pin 43 in bearing relationshipso that the cylinder barrel is fixed for rotation about the axis 93 ofthe pin 43.

The cylinder barrel 90 is universally connected to the swash mechanism95 of the pump 10 by pistons 96 reciprocable in cylinders 97 formed inthe barrel and a constant speed gear joint 98. Rotation of the swashmechanism 95 by the drive shaft 16 consequently effects synchronizedrotation of the cylinder barrel 90 in the housing 48, at a constantspeed.

The swash mechanism 95 rotates the cylinder barrel in a clockwisedirection (as viewed in FIGURES 3 and 4). As it does so, the pistonheads 100 of the pistons 96 are introduced to and withdrawn fromcorresponding cylinders 97 in a well known manner. Fuel is drawn intoeach cylinder 97 through its conventional cylinder port 101 from thepump inlet port 11 as the corresponding cylinder 97 moves through 180from top dead center, as seen in FIGURE l, to bottom dead center. Thefuel is then expelled through the same cylinder port 101 to the pumpoutlet port 12 as the same cylinder 97 moves through 180 from bottomdead center to top dead center.

As the pump 10 operates in this manner, a certain amount of fluid underpressure leaks from the cylinders 97 between the bearing surface 80 onthe plate 76 and the bearing face 91 on the barrel 90. This leakageprovides lubrication for the rotating barrel 90. At the same time,however, leakage pressure tends to urge the cylinder barrel 90 away fromthe bearing plate 76. During normal operation of the pump 10, however,operating pressure in the cylinders 97 is effective on the pressureresponsive areas 102 adjacent the cylinder ports 101 within thecylinders to create a pressure unbalance effect on the cylinder barrel90 in the direction of the bearing plate 76 and hold it against theplate. Accordingly, leakage is not a significant factor during normaloperation.

This optimum pressure unbalance is not effective during starting andinitial operation of the pump 10, however. At such time there is atendency for the cylinder barrel 90 to unseat from the bearing surface90 on the plate 76 and allow a heavier film of fluid under pressure tobe interposed between the bearing surface 80 and the bearing face 91.Excessive leakage subsequently occurs if such unseating is permitted.

In addition, when rapid changes of displacement of the pump 10 areeffected by the displacement control system 105 during operation of thepump, the gyroscopically rotating cylinder barrel 94 tends to precessand thus seeks to effect an unseating of the cylinder barrel from thebearing plate 76. In this light, the displacement control system variesthe angular relationship of the cylinder mechanism 33 to the swashmechanism 95 in a wellknown manner. Since it forms no specific part ofthe present invention, a detailed description of the displacementcontrol system 105 is not thought to be necessary.

The aforedescribed unseating tendencies of the cylinder barrel 90 areprevented in the pump 10 by locking the cylinder barrel for rotationagainst the bearing plate 76 according to the present invention. A firstform of cylinder barrel locking arrangement embodying features of thepresent invention is illustrated in FIGURES 1-5 and includes an annularfrusto-conical abutment surface 111 on the abutment 112 formed from theinside of the skirt 113 of the cup-shaped housing 40. The cylinderbarrel 90 rotates freely within the confines of the abutment 112 and hasan annular channel 116 formed in its periphery in axial registry withthe abutment surface 111.

Seated on the frusto conical abutment surface 111 so that it extendsradially into the annular channel 116 in the barrel 90 is a locking ring120. The locking ring 120 is preferably fabricated of an alloy steel andhas a frusto-conical outer surface 121 formed on its periphery andcomplementary with the frusto-conical abutment surface 111. The lockingring 120 is split so as to define opposed free ends 122, as seen inFIGURE 3, and the uncompressed outside diameter of its frusto-conicalsurface 121 is slightly greater than the inside diameter of thefrusto-conical abutment surface 111. Accordingly, the natural resiliencyof the alloy steel ring 120 causes it to ride inwardly of the housing 48on the frusto-conical surface 111 in the direction of the bearing plate76.

The effect of the foregoing is to urge the annular planar upper surface125 on the ring 120 into engagement with the complementary annularplanar shoulder surface 126 in the channel 116. Thus, the locking ring120, which is compressed slightly when it is initially seated on thefrusto-conical surface 111, constantly biases the cylinder barrel 90into engagement with the bearing plate 76.

The ring 120 is snapped into the position illustrated in FIGURE l, forexample, by compressing it radially and forcing it past the abutment 112from the open end of the housing 40. To this end, complementary annularbevelled surfaces 130 and 131 are formed on the ring 120 and theabutment 112, respectively. The ring 120 is sprung past the abutment 112while already seated in the channel 116 of the cylinder barrel 90, thuslocking the cylinder barrel 90 into place.

The split ring 120 is prevented from rotating with the cylinder barrel90 by a pin 135 removably seated in a suitably formed aperture 136extending through the skirt 113 of the housing 40 between the opposedends 122 of the ring (see FIGURE 3). It will thus be seen that theopposed annular planar surface 125 and 126 on the ring 120 and in thechannel 116, respectively, slide relative to each other in bearingrelationship as the cylinder barrel 90 rotates. The bearing surfaces 125and 126 are lubricated by the fluid being pumped through the slightleakage hereinbefore referred to and the effect of centrifugal forceupon it. Friction between the locking ring 120 and the cylinder barrel90 is thus kept at a minimum.

The positioning pin is of a diameter which permits only a prescribedamount of radial compression of the ring 120 before the ends 122 of thering engage the pin. Accordingly, regardless of the force exerted on thering by the cylinder barrel 90 attempting to unseat itself from thebearing plate 76, the ring 120 compresses only to that point wherein itsfree ends 122 contact the positioning pin 135, and then the cylinderbarrel 90 can force it outwardly no further. Unseating of the cylinderbarrel 911 beyond a prescribed limit is thus prevented.

To permit removal of the cylinder barrel 90 from the housing 4.0, aseries of three access ports 140 are formed in the skirt 113 on thehousing 48 in axial registry with the locking ring 120, as seen inFIGURE 3. By inserting any suitable tools through each of the accessports 140, the ring 120 can be compressed inwardly in the channel 116and the cylinder barrel 90 drawn freely out of the housing 40. Thepositioning pin 135 must be removed in such case, of course. In thismanner, simple mounting and removal of the cylinder barrel 90 is readilyfacilitated.

Referring now to FIGURE 6, a second form of cylinder barrel lockingarrangement embodying features of the present invention is illustrated.generally at 210. The locking arrangement 210 is identical to thecylinder barrel locking arrangement `111) hereinbefore discussed withbut one significant exception. The locking ring 220 of the lockingarrangement 210 is constructed so that the outside diameter of itsfrusto-conical outer surface 221 is slightly less than that of thecorresponding surface 121 in the locking arrangement 1111. Accordingly,the frusto conical surface 221 seats on the annular frustoconicalsurface 111 formed within the skirt 113 of the housing 4t) in radiallyuncompressed relationship and does not constantly urge the cylinderbarrel 90 into bearing relationship with the bearing plate 76. Inpractice, a space of about .001 inch in width, as at 224, is normallyleft between the upper surface 225 on the ring 220 and the uppershoulder surface 126 in the channel 116.

Because the locking ring 22@ is not constantly urged into engagementwith the cylinder barrel 90, the cylinder barrel 90 rotates insubstantial frictionless relationship with the locking ring 221D.Nevertheless, the barrel 91B cannot move more than approximately .001inch from the bearing plate 76 before it engages the locking ring 2211and any subsequent or additional tendency to unseat on the part of thebarrel 90 is opposed by the resilience of the ring 220.

It should now be seen that with either form of locking arrangement (110or 210) embodying features of the present invention, unseating of thecylinder barrel 90 from the bearing surface on the plate 76 is firstresiliently opposed and, collaterally, prevented. The tendency for thebarrel 91D to unseat and permit substantial fiuid leakage from thecylinders 97 is significant during starting of the pump and when rapidchanges of displacement are effected by the displacement control system105, as has been pointed out. Regardless of causation, however, thepresent invention obviates the effect of any unseating tendency.

In the operation of the pump 10, it has been pointed out that thecylinder barrel 90 is rotated by the swash mechanism 95 through thepistons 96 and the constant speed gear joint 98. At the same time, thecup-shaped housing 40 of the cylinder mechanism 33 is seated for pivotalmovement against a retaining ring 150 overlying the swash mechanism 95.

The retaining ring 150 overlies the swash plate 151 which is formed of arelatively stiff bronze such as Muler 600 or the like. The swash plate151 is mounted in thrust bearing relationship on a Teflon disc bearing152 seated in the end cap 22 of the pump casing 15. The neck 153 of theswash plate 151 has a shaft receiving bore 154 axially formed therein,and is splined at 155 to receive the correspondingly splined drive shaft16. A face seal assembly 159 prevents loss of fiuid from the interior ofthe casing 15.

Three slipper bearings 165 are seated within the cap 22 radially of theswash plate 151, as best seen in FIG- URES 1 and 4. These slipperbearings 165 provide radial bearing surfaces 166 for the peripheralbearing surface 167 on the swash plate 151. The slipper bearings 165 aremounted along one 60 segment of the circumference of the swash plate 151since radial thrust is effective only in that direction, of course. Theslipper bearings are held in place by the retaining ring 150hereinbefore referred to. The retaining ring 150 is, in turn, heldbetween the cap 122 and the body 2t) of the casing 15.

The swash plate 151 has segmentally spherical recesses 170 formed in itsouter surface 171 for receiving the ball ends 172 on the pistons 96. Theball ends 172 are forced into the sockets 170 past the slightlyresilient inwardly inclined lips 173 formed from the bronze material ofthe swash plate 151 around the sockets 170. The lips 173 hold the ball172 in place in corresponding sockets 170.

The gear-type constant velocity joint 98 hereinbefore referred toincludes a ring carrying a plurality of external gear teeth 181 andkeyed to the periphery of the swash plate 151, as illustrated. The gearteeth 181 mesh with the internal gear teeth 185 formed in the outer endof a cage 186 secured at its inner end to the periphery of the cylinderbarrel 91) by conventional key means. The teeth 181 and 185 arepreferably double helical teeth and, consequently, assure constantvelocity synchronized rotation of the swash plate 151 and the cylinder911. Such a gear teeth arrangement is illustrated in Wahlmark Patent No.3,013,411, entitled, Gear Type Constant Velocity Joint.

It should now be recognized that an improved fiuid device of the swashplate type, incorporating new and improved barrel locking arrangements,has been described and illustrated. Although the swash plate type fiuiddevice of the present invention is described herein in terms of avariable displacement pump 10, the device might as readily be a fixedplacement pump or a fixed or variable displacement motor, as has beenpointed out. The cylinder barrel locking arrangements 110 and 210embodying features of the present invention are suitably adaptable toall such swash plate type fiuid devices. In this context, however, witha fixed displacement Huid motor or the like, the bearing plate 76 uponwhich the cylinder barrel 90 rotates in bearing relationship is normallyseated against a fixed housing, usually the end of the fiuid motorhousing itself.

While several embodiments described herein are at present considered tobe preferred, it is understood that various modifications andimprovements may be made therein, and it is intended to cover in theappended claims all such modifications and improvements as fall withinthe true spirit and scope of the invention.

What is desired to be claimed and secured by Letters Patent of theUnited States is:

1. In a swash plate type fluid device including a swash mechanismoperatively connected to a cylinder barrel, wherein the cylinder barrelis normally seated for rotation against the bearing surface provided inhousing means, the improvement in barrel locking arrangement comprising:abutment means disposed circumferentially of said barrel in said housingmeans, shoulder means on the periphery of said barrel in opposedrelationship to said abutment means, a locking ring disposed betweensaid `abutment means and shoulder means for preventing unseating of saidbarrel from properly seated relationship on said bearing surface, saidlocking ring having a gap formed therein so as to define a split ring,and positioning means extending into said gap for fixing it againstrotation with said barrel.

2. The improvement in cylinder barrel locking arrangement of claim 1further characterized in that said split locking ring is radiallyresilient and has a frustoconical outer surface formed thereon, and acomplementary frusto-conical abutment surface formed on said abutmentmeans, said ring resiliently opposing said unseating of the barrel fromthe bearing surface.

3. The improvement in cylinder barrel locking arrangement of claim 2further characterized in that said gap has a first predetermined width,said positioning means being of a second predetermined width less thansaid first predetermined width whereby resilient radial compression ofsaid ring is limited by said positioning means.

4. In a swash plate type fluid device including a swash mechanismoperatively connected to a cylinder barrel, wherein the cylinder barrelis normally seated for rotation against a bearing surface provided inhousing means, the `improvement in cylinder barrel locking arrangementcomprising: abutment means disposed circumferentially of said barrel insaid housing means, shoulder means on the periphery of said barrel inopposed relationship to said abutment means, a split locking ringdisposed between said abutment means and said shoulder means forpreventing unseating of said barrel from properly seated relationshipagainst the bearing surface, a frustoconical outer surface formed onsaid ring and a complementary frusto-conical abutment surface formed onsaid abutment means, whereby said ring is compressed radially bymovement of the barrel from the bearing surface.

5. The improvement in cylinder barrel locking arrangement of claim 4further characterized in that said frustoconical outer surface of saidring has a first predetermined normal diameter, and said complementaryfrusto-conical abutment surface has a second predetermined diameter,said first predetermined normal diameter being slightly larger than saidsecond predetermined diameter whereby said ring is radially compressedwhen properly seated between said shoulder means and said abutment meansso as to constantly urge said `barrel against the bearing surface.

6. The improvement in cylinder barrel locking arrangement of claim 4further characterized in that a gap is normally defined between saidlocking ring and said shoulder means whereby said cylinder barrelrotates freely of said ring in normal operation of the device.

7. In a swash plate type fluid device including a swash mechanismoperatively connected to a cylinder barrel, wherein the cylinder barrelis normally seated for rotation against a bearing surface provided inhousing means, the improvement in cylinder barrel locking arrangementcomprising: an annular abutment formed within said housing meanscircumferentially of said barrel, a channel formed in the outerperiphery of said barrel in axial alignment with said abutment, aradially planar surface defined by said channel, a first frusto-conicalinner surface formed on the inner periphery of said abutment, a splitlocking ring seated in said channel, a first frustoconical outer surfaceformed on the outer periphery of said ring, and a radially planarsurface formed on said ring, said frusto-conical surfaces mating so thatsaid radially planar surfaces are in oppositely disposed relationshipwhereby any tendency of the barrel to unseat from the bearing surface isopposed by engagement of said `radially planar surfaces and the radialresilience of said ring.

8. The improvement in frusto-conical barrel locking arrangement of claim7 further characterized by and including a second frusto-conical innersurface formed on the inner periphery of said abutment and a secondfrustoconical outer surface formed on the outer periphery of said ring,said second frusto-conical surfaces coming into engagement when thebarrel is seated in the housing means whereby said ring is initiallycompressed to permit seating of the barrel against the bearing surfaceand expansion locking of said ring into an engagement condition betweensaid rst frusto-conical surfaces.

9. In a swash plate type fluid device including a swash mechanismoperatively connected to a cylinder barrel, wherein the cylinder barrelis normally seated for rotation against a bearing surface provided inhousing means, the improvement in cylinder barrel locking arrangementcomprising: abutment means disposed circumferentially of said barrel insaid housing means, shoulder means on the periphery of said barrel inopposed relationship to said abutment means, and a radially resilientsplit locking ring disposed between said abutment means and saidshoulder means for preventing unseating of said barrel from properlyseated relationship on said bearing surface, said split locking ringhaving a frusto-conical outer surface formed thereon, and acomplementary frusto-conical inner surface formed on said abutmentmeans, said frustoconical surfaces mating to compress said ring andresist unseating of said barrel as said barrel tends to back off fromsaid bearing surface.

10. In .a swash plate type fluid device, housing a means having abearing surface therein, a cylinder barrel rotatable in seatedrelationship on said bearing surface, and means for holding said barrelin properly seated relationship on said bearing surface, said holdingmeans consisting solely of abutment means disposed circumferentially ofsaid barrel in said housing means and shoulder means on the periphery ofsaid barrel in opposed relationship to said abut-ment means with aradially resilient snap ring disposed between said abutment means andsaid shoulder means, said ring being fixed against rotation with saidbarrel, and opposed frusto-conical surfaces on said ring and one of saidabutment means and said shoulder means, whereby said barrel is preventedfrom departing said properly seated relationship by resilient radialflexing of said ring effected by cooperation between said frusto-conicalsurfaces as said barrel attempts to back off from said bearing surface.

References Cited by the Examiner UNITED STATES PATENTS 1,817,080 8/1931Howard 103-162 3,185,105 5/1965 Headings et al 103-162 3,194,172 7/1965Schottler 103-162 MARK NEWMAN, Primary Examinez'.

SAMUEL LEVINE, Examiner.

R. M. VARGO, Assistant Examiner.

1. IN A SWASH PLATE TYPE FLUID DEVICE INCLUDING A SWASH MECHANISMOPERATIVELY CONNECTED TO A CYLINDER BARREL, WHEREIN THE CYLINDER BARRELIS NORMALLY SEATED FOR ROTATION AGAINST THE BEARING SURFACE PROVIDED INHOUSING MEANS, THE IMPROVEMENT IN BARREL LOCKING ARRANGEMENT COMPRISING:ABUTMENT MEANS DISPOSED CIRCUMFERENTIALLY OF SAID BARREL IN SAID HOUSINGMEANS, SHOULDER MEANS ON THE PERIPHERY OF SAID BARREL IN OPPOSEDRELATIONSHIP TO SAID ABUTMENT MEANS, A LOCKING RING DISPOSED BETWEENSAID ABUTMENT MEANS AND SHOULDER MEANS FOR PREVENTING UNSEATING OF SAIDBARREL FROM PROPERLY SEATED RELATIONSHIP ON SAID BEARING SURFACE, SAIDLOCKING RING HAVING A GAP FORMED THEREIN SO AS TO DEFINE A SPLIT RING,AND POSITIONING MEANS DEFINING INTO SAID GAP FOR FIXING IT AGAINSTROTATION WITH SAID BARREL.